#include<stdio.h>
#include<string.h>
int main()
{
    char a[101],b[101];
    int mid,len,i,top,next;

    gets(a);
    len=strlen(a);
    mid=len/2;

        top=0;
    for(i=0;i<=mid;i++)
        b[top]=a[i];

    if(len%2==0)
        next=mid;
    else
        next=mid+1;

      for(i=next;i<=len;i++)
      {
          if(a[i]!=b[top])
            break;
          top--;
      }
       if(top==0)
        printf("YES");
    else
        printf("NO");

    getchar();getchar();
    return 0;
}
